Denial-of-service attacks is a class of cyber threats specifically designed to disrupt the availability of a networked system, service, or resource to its legitimate users. As a research concept and academic field, it investigates the various methodologies employed by malicious actors to overload or exhaust system capacities, network bandwidth, or application resources, thereby preventing normal operation. Key characteristics studied include the diverse attack vectors utilized, such as resource exhaustion or protocol manipulation, and the challenges associated with detecting and mitigating these distributed and often high-volume disruptions. Its significance lies in the critical need to understand and counter threats to digital infrastructure resilience, informing advancements in network security, system design, and cybersecurity policy.